Over the years, hydraulic motors have been commonly utilized for a wide variety of commercial and industrial applications It is generally known that, depending upon the design parameters thereof, such motors are capable of developing very high torque. For certain applications, such as the leading edge flap system of aircraft, hydraulic motors are highly advantageous.
However, hydraulic motors for applications such as aircraft leading edge flap systems have typically had a fixed wobbler angle. In other words, it has been conventional for such hydraulic motors to be of the fixed displacement type primarily due to the fact that variable displacement motors must utilize expensive and complex pressure drop sensors that sense a drop in pressure across the motor and then hydraulically change the wobbler angle in order to vary displacement. In order to avoid the expense and complexity of such systems, it has been typical to rely upon a fixed displacement hydraulic motor.
Unfortunately, this means that the hydraulic motor must be designed to handle the highest load that can be expected. Thus, in the case of a leading edge flap system on an aircraft, the displacement of the motor must be quite high in order to handle any unexpected but potentially encountered high load. But this is undesirable inasmuch as there is normally a significant excess in load capacity.
As a result, the hydraulic motor requires a high rate of flow even under low load conditions which puts a substantial burden on the overall aircraft hydraulic system. For these reasons, there has again been more attention focused in recent years on utilization of variable displacement hydraulic motors.
But as previously mentioned, this has been undesirable due to the complexity, expense and reliability of known control systems for variable displacement hydraulic motors. It has generally been recognized that an electronic controller is required which functions with the sensors and hydraulic valves to hydraulically change the wobbler angle with changing load conditions. While this does achieve the objective of minimizing the burden on the aircraft hydraulic system, it is nevertheless unsatisfactory from a cost, maintenance and safety standpoint.
The present invention is directed to overcoming the above stated problems and accomplishing the stated objects.